1. Field of the Disclosure
The present invention relates primarily to apparatus for use as a heat pump, and in particular but not exclusively apparatus configured to use atmospheric air as its heat source when operating as a heat pump. In addition, apparatus according to the present invention may also be configured for use as a refrigerator (e.g. air-conditioning unit) or a heat engine.
2. Brief Description of Related Technology
Conventional heat pumps used for heating buildings or the like use a working fluid operating in a closed vapour cycle and generally draw their heat supply from either the ground or a water reservoir, via a heat exchanger. The heat exchangers used in such arrangements are generally separated from the heat pump itself and are often of considerable size, particularly if ground-sourced or requiring a source of still or running water. The working fluid of such devices usually works in a closed cycle and the heat obtained from the heat exchanger is pumped to the thermal load via another heat exchanger. The coolants/refrigerants commonly used as working fluids in such heat pumps are often potential pollutants.
The use of atmospheric air as the heat source in a heat pump is known in the art, but generally requires use of inefficient aerodynamic compressors (or blowers) to handle the high volumetric flows required as a result of the low energy per unit volume of ambient air. The heat exchange elements deployed in such arrangements are also generally vulnerable to ice accretion due to moisture within the air.